POTS (Postural Orthostatic Tachycardia Syndrome)

Definition: Postural Orthostatic Tachycardia Syndrome (POTS) is a disorder characterized by a significant increase in heart rate upon standing.
Prevalence: It's relatively common, affecting about 1 in 500 individuals, typically presenting in late adolescence or early adulthood, with a higher prevalence in females (4:1 ratio, female to male).

Cardiovascular Symptoms:
- Lightheadedness: Patients often feel dizzy or lightheaded upon standing.
- Palpitations: A feeling of a rapid, fluttering, or pounding heart.
- Exercise Intolerance: Difficulty in engaging in physical exercise due to fatigue or other symptoms.
- Syncope (in some cases): Fainting or passing out, though this occurs in a minority of patients.
Non-cardiovascular Symptoms:
- Fatigue: Chronic tiredness that doesn't improve with rest.
- Anxiety: Increased feelings of worry, nervousness, or unease.
- Tremor: Unintentional, rhythmic muscle movements.
- Headache: Frequent or chronic headaches.
- Mental Cloudiness ("Brain Fog"): Difficulty thinking, concentrating, or remembering.
- Gastrointestinal Issues: Including nausea and bloating.

Onset of symptoms may follow:
- Viral infections
- Pregnancy
- Surgery
- Intense psychological stress

Subtypes:

Neuropathic POTS: Believed to be due to a dysfunction in the peripheral sympathetic nervous system.
Hypovolemic POTS: Characterized by low blood volume and often treated with fluid and salt supplementation.
Hyperadrenergic POTS: Associated with high levels of adrenaline and noradrenaline, leading to an overactive sympathetic nervous system.

Initial Step: Suspecting POTS is crucial as it's often overlooked in medical training.
Diagnostic Criteria:
- Sustained heart rate increase upon standing (by at least 40 beats per minute if aged 12-19, or at least 30 if 20 or older).
- Reproducible symptoms with standing.
- Absence of orthostatic hypotension (in other words, without a significant drop in blood pressure.)
Diagnostic Tests:
- Tilt Table Test: A key diagnostic test where the patient's heart rate and blood pressure are monitored while the angle of the table is changed to simulate standing up.
- Additional Tests: May include blood tests to rule out anemia, thyroid function tests to rule out hyperthyroidism, and electrocardiograms to check for other heart conditions.

Multidisciplinary Approach: Involving physicians, psychologists, and physical/occupational therapists may be beneficial.
Activity/Exercise:
- Exercise training, especially routines that avoid the upright position initially.
- Weight training focusing on legs and core.
Volume Expansion:
- Increasing water and salt intake.
- Compression stockings to prevent venous pooling of blood in the legs.
Medication:
- Various medications acting on the autonomic nervous system, including beta blockers, vasoactive agents, and others.
- For example:
  - Mitodrine
  - Propranolol
  - Evabradine
  - Clonidine
  - Pyridostigmine
Treatments to Avoid: Sinus node modification procedure is not recommended as it can worsen symptoms and risk making the patient pacemaker dependent.

Improvement Over Time: Many patients experience a gradual improvement in symptoms over time, although the timeline can vary widely.
Long-term Management: Some patients may require long-term management of symptoms, including ongoing physical therapy and medication.
Quality of Life: With appropriate treatment and management, many patients are able to maintain a good quality of life despite ongoing symptoms.
Mortality: There have been no known deaths directly attributable to POTS, indicating that while the syndrome can significantly impact quality of life, it is not known to be life-threatening.